Method of and apparatus for cold rolling strip material



Jan. 12, 1937. w, TRlNKs 2,067,514

METHOD OF AND APPARATUS FOR COLD ROLLING STRIP MATERIAL Filed July 22, 1955 2 Sheets-Sheet 1 Jan. .12, 1937. R NKs 2,067,514

METHOD OF AND APPARATUS FOR COLD ROLLING STRIP MATERIAL Filed July 22, 1933 2 Sheets-Sheet 2 yes FF-H

Patented Jan. 12, 193'? "UNITED 4 STATES ration of Pennsylvania Application July 22, 1933, Serial No. 681,693'

This invention relates. generally to 'cold rolling, but more particularly to the cold rolling of strip material. In employing the term strip" or strip material, I make no distinction between strips and sheets, since I may employ. my improved procedure 'in the cold rolling of any strip material independently of its width and final thickness.

In all cold'rolling operations; and particularly where ferrous metals are involved, considerable heat is developed, due to the internal deformation of the metal rolled and to the slippage of the deforming rolls on the metal as well as to plastic deformations in the rolls themselves, This has long been recognized and various expedients have been employed for overcoming the detrimental effects occasioned thereby. In the past, cold rolling operations have been limited to low speeds or to small reductions, prition'provides more time forabstracting or dissi-' pating the mechanically generated heat than a.

fast rolling operation. Where heat is developed by the rolling operation more rapidly than it is; abstracted or dissipated, numerous detrimen tal effects are encountered; such as loss of hardness of the roll surface, surface spelling and. change of roll contour, "due to uneven thermal expansion. This not only decreases the effective vlife of the rolls, but also injuriously affects the rolhng operation and the spalling detrimentally affectsv the surface of the sheets or strips rolled. Where slow speed rolling is employed, the time element may be sufllcient to minimize these and other dimculties, particularly if some ordinary expedients are employed for carrying away at; least some of the; mechanically generated heat, and it -has therefore been the practice to either externally or internally cool the rolls by a flow of cooling liquid.

I have, however, discovered that rolling friction or skin friction is responsible for a large part of the mechanically generated heat. By the term rolling friction I refer to the friction occasioned, by the relative slipping'between the roll surfaces and the material being rolled. It -is, of course, apparent that this rolling friction contributes to roll wear and also has some efi'ect in rougheningthe roll surfaces. In my opinion, it also occasions surface hardening of the strip material rolled and increases the directional 24 01am. (c1. -60) The use ofa'n difierence of physical properties. of the rolled material, such, for example, as ductility; The most serious effect of roll friction is encountered,

in rolling thin material, such as sheets or strips,

an extent commensuratewith the pressures em-.

, ployed. I

From the foregoing it is apparent that it is not ,only' essential to dissipate the mechanically generated heat in order to obtain the 'bestresults in a rolling operation, but it is also atleast highly desirable to-minimize rolling friction or skin friction, and thus to some extentminimize the cause for the detrimental effects encountered,

In the past, water has been used as a coolant in rolling operations and it isexcellent for that purpose, but it has very little effect as a lubricant especially under the pressures encountered in cold rolling operations, Oil, 'on the other hand, as heretoforeemployed'in cold rolling op- 'erations, hasthe desired effect as a lubricant,

but itis; ineffective as a. coolant.

In order to obtain the desired cooling effect and at the same time minimize rolling friction,

I employ a cooling'fluid having a high lubricatingcharacteristic and also having the capacityfor absorbing heat at a relatively rapid rate and such a fluid is referred to throughout this application by the term cooling lubricantfi ulsion of oil in water is old and is not claimed as part of the present invention. a

The temperature of the strip attained in any given roll pass is directly related to the temperature of the sheet material entering the pass,

the degree of deformation of the material in the pass, and rolling or skin friction.

From the foregoing, it is apparent that the temperature of the material entering the pass contributes to the temperature of the material leaving the pass, with the result that under ordinary conditions of rolling, the heating effect is cumulative,

-sinc'e ordinary means of cooling, such as heretosive'passes enters at progressively higher temperatures.

It is. of course, apparent that the length 'of event, ordinary variations in stand spacingwill not vary the time interval'between passes sufliciently to make a material difference in the amount of heat dissipated or removed from the material by atmospheric absorption.

From the foregoing it will be apparent that where fast'rolling. is employed, the surface temperatures of the rolls rise excessively and, in a continuous mill, vary greatly from pass to pass even where the ordinary expedients for abstractheat are employed. The resulting expansion p of the rolls not only varies from the middle toof gauge or thickness of the material rolled.

. ward the ends of the rolls, but also varies from time to time and from pass to pass and thus makes it extremely difflcult to maintain constancy Then'too, as I have stated, these excessive temperature changes produce excessive stresses in the rolls themselves, which result in cracking or spalling of the roll surfaces, as well as in drawing 'the temper and reducing the hardness of the surfaces. These detrimental eifect s are likewise encountered in a reversing mill, and particularly where a high output per mill is sought and the strip material is reeled between passes,

because the reeling operation in itself conserves the heat within the material and the intervals between passes are necessarily not much longer than the intervals between passes in a continuous mill or, in any event, are not long enough to prevent the cumulative heating effect in both the material and 'the rolls. It is, therefore, highly desirable to maintain the strip material at as low a temperature as possible during the cold rolling operation whether a continuous or a reversing mill is employed, and to presentthe material to each. .pass at as nearly as ossible the tem-' perature of its presentation to he preceding pass in order to avoid this objectionable cumulative effect of the mechanically generated heat.-

In carryingout the procedure constituting my improved method of rolling, I may employ either -a continuous mill or ajreversing mill, and I also employ means for, in efiect, cooling the strip material'by turbulent streams of cooling lubricant moving rapidly relative to the strip and under pass, is" largely abstracted and dissipated before such conditions that the heat mechanically generated within the material, as it traverses each the material is subjected to the deforming and heating effect. of a subsequent pass. For bestresults, the cooling lubricant must have a temperature only slightly above the freezing point of water. A i l.

The primary object of my invention is to produce a method of cold rolling and'apparatus for carrying out that method, such as will overcome difliculties'usually encountered in connection with rapid rolling under normal commercial condi tions.

Figure 1 is a. diagrammatic view of apparatus embodying my invention shown in connection with a side elevation of a reversing mill and.

' crating machine, from an economic standpoint adapted to carry out the process herein defined in connection with' a reversing mill; Fig. 2 is a plan view of the apparatus shown in Fig. 1, the reversing mill there illustrated being shown in section for convenience of illustra- 5 tion;

Fig. 3 is a diagrammatic illustration of'adjacent stands of a continuous mill and illustrates apparatus for carrying out my improved process as applied to such stands; the apparatus being shown in section for convenience of illustration; and

Fig. 4 is a plan view of the apparatus shown in Fig. 3, and in which the stands of the adjacent mill are shown in section for convenience of illustration. I

In the illustrated embodiments of my invention, I employ means for spraying a refrigerated cooling lubricant onto the strip material as it leaves the working rolls and also onto the working rolls. Where theinvention is carried forward. in connection with a. reversing mill, the

means above referred to are so located and arranged that the material issuing from either side of the mill is subjected to the spray of refrigerated cooling lubricant.

In carrying out my invention, .1 preferably employ a cooling lubricant, for the double purpose .of minimizing rolling friction and also absorbing mechanically generated by the passage of the material through each roll pass. The lubricant thus refrigerated is, as previously stated, herein referred to as cooling lubricant.

- The apparatus employed includes a source of cooling lubricant underpressure, herein diagrammatically disclosed as'a' pump 5; a cooler 6, through which the lubricant from. the source of pressure is delivered, and a series of spray nozzles 'so arranged that the cooling lubricant is delivered in the form of pressure jets to the material rolled, and also to the surfaces of the working rolls. I preferably divide the nozzles into groups so arranged that the cooling lubricant is delivered to both sides of the strip at substantially the zone of contact between the rolls and the strip and also along the strip as it leaves the rolls so thatthe materialis, in effect submerged by a rapid flow of cooling lubricant for a suflicient period to insure adequate cooling. In order to assure the abstraction of substantially all of the h'eat generated, I a employ a refrigeratoror refrigerating machine I, which, as diagrammatically illustrated, is so arranged that it refrigerates the cooling medium delivered to the cooler 6. It will, of course, be understood that this cooling medium may be any non freezing liquid, such as brine or liquefied animonia, since my purpose is to cool the lubricant, i. e., the-cooling.lubricant employed, to a temperature of about 32 F.

' While it is possible during the winter months to use cold water from rivers or lakesas a cooling medium to remove heat'from the cooling lubricant, and thus, 'to dispense with the refrigthis is not in most cases feasible, because the 7 water cannot ordinarily have a temperature below 32 degrees Fahrenheit. In endeavoring to .cool a lubricant to nearly the same temperature, the temperature gradient will be very small, and

the heat-exchange apparatus required will be so excessively bulky and expensive as tobe commercially impracticable. Furthermore, such apparatus can only be. used during the few months of the year when water is available near a freezing temperature; and, since it is desired to roll material throughout the year, a refrigerating machine will be required to, inmost cases, permit operation during the other months.

Fig. 1 I have diagrammatically illustrated a reversing mill, including a frame 9, top and bottom backing rolls l0, and top and bottom working rolls II. It will be understood that the mill is provided with the usual bearings, screw downs and other accessories, and fiiat .while a four-high is illustrated, the invention may be carried forward with any type ofmill suitable for the rolling conditions encountered. .A'sil lustr'ated, the mill is equipped with coiling reels I2, located on opposite sides of the frame .25 portion thereof, and is also provided with suitalso from the rolls themselves, I-provide a se' :ries of nozzles on. each side of the mill which,

I for convenience of description, may be said to be divided into three groups, viz., the nozzles .40 M which are arranged to spray refrigerated lubricant onto the face of the rolls II and consequently onto the material l5 being rolled at a point adjacent to the zone of contact between the rolls and the material. In the illustrated 45 embodiment, the guides I3 are hollow'and are provided with apertures which constitute nozzles MQ'arrangedto deliver the'refrigerated lubricant onto the material as it leaves the pass. A third group of nozzles I4" are located within 50 ,and are spaced around the casing NS for each reel l2. A reference to Figure 2 discloses that- 7 the' nozzles |4 are located in spaced relation along the rolls II and that the spacing is such that'the jets of liquid issuing therefrom will '55 spread sufliciently to, in effect, submerge the entirelength of, each roll ll by a rapidly movzing film of lubricant which, because of the'force 4 of the jets, is impelled onto the material l5 being rolled. The apertures constituting the K nozzles I4 are similarly Spaced transversely of the strip material l5, and are so spacedalong .that material as to provide a copious flow of cooling lubricant on both the upper and the lower surfaces thereof. A similar transverse spac- ,55 ing of the nozzles H" is employed, and these nozzles are also located around substantially the entire periphery of theassociated reel l2-so that the material is continuously subjected to a flow of cooling lubricant from the time it leaves the 7 pass until the coiling operation is completed.

From the foregoing it Will be apparent that all of the nozzles M, M and M are included V as a part of, a pressure system, whichalso includes the pump 5 and the cooler 6.-

7 In order to avoid. waste of cooling lubricant,

relative to the material.

I employ catch basins so arranged as to collect the lubricant as it drops from the rolls, the material being rolled and the material being coiled, and these basins form a source of cooling lubricant supply for the pump 5. As shown, one such basin I1 is located below the bottom backing roll -l0 and a similar basin may be located below each reel 01' may form a part of the casing [6 of each reel. Each of these basins is provided with a submerged outlet port which communicates through suitable piping l8 with the inlet to the pump 5. With this arrangement the cooling lubricant delivered to the rolls II and the material I5 is collected in the several basins, is returned to the pump 5 and is forced under pressure through, the cooler 6 and back to the nozzles.

In order to provide access to the reels, the

casings l6 are provided with a hinged, portion which is capable of I being moved to the dotted line position shown in the right hand portion of Fig. 1. This necessitates a joint in the piping to such of the nozzles M" as are supported by the hinged cover.

In order that the mill of Figures 1 and 2 may be operated as a reversing mill, (the cooling facilities above described are located on both sides thereof, and it .will be apparent that by properly setting the valves l9, IS, the .flow of co'oling lubricant can be so controlled that only the nozzles on the delivery side of the mill are effective. It will, however, be apparentv that under some conditions of operation it may be desirable to deliver the cooling lubricant to both sides of the mill in order to insure the desired cooling of the material prior to entering the ,pass, and I also call attention to the fact, that the nozzle arrangement is such that the material being cooled is not only subjected to the flow of cooling lubricant during the coiling operation, but that this flow may be continued after the coiling operation is completed and under such conditions that the entire coil is, in effect, submerged by a relatively rapid flow of cooling lubricant.

In Figures 3 and 4 I have shown an arrangement of apparatus adapted for carrying out my invention in connection with a continuous mill. In those views I have illustrated but two stands of the continuous mill, but it will be understood that the invention may be applied to each of the several stands of such a mill. As there illustrated, each stand comprises a frame 2|, work-- ing rolls 22, backing rails 23 and such auxiliary devices and accessories as are ordinarily employed in such mills. Each stand is also provided with entering guides 24 and a table 25 is located between the stands and forms a means of support for the material l5 being rolled and passing between the two adjacent stands. As described in connectionwith Figures 1 and 2, the cooling system includes separategroups of nozzles so arranged that the strip material I5 is, in effect, subjected to a submerging flow of coolinglubricant throughout the entire rolling operation,' the lubricant moving; at high velocity As shown, each roll stand is provided with four groups of nozzles, viz., nozzles 26, which deliver cooling lubricant onto the rolls 22 in such'a way that the surface of the rollsand the entire width of strip material entering the pass are both submerged by the flow; nozzles 26 are formed in the hollow guides 24, as described in connection with Figures 1 and 2;

60 cooling lubricant -and of guiding the same into these nozzles are supplemented by a series of nozzles 26"; and each roll stand is provided with nozzles 21 located on the delivery side thereof.

and which cooperate with the nozzles 26, 26' and v 26 associated with'the adjacent stand, in insuring that the entire length, of strip material from one stand to another is in effect submerged 25. which is provided with a submerged outlet port.

by the flow of cooling lubricant. It will be apparent from the drawings that the nozzles 'referredto are located both above and below the a strip material being rolled, and for this reason,

[substantially the same relationship as in Figure 2.

In order to avoid waste of the cooling lubricant, I also provide basins 29 and 30, each 9f which; in efiect, forms a source of supply for the pump 5'. These outlet ports communicate with the inlet of the pump 5 through conduits l8 and the. nozzlesabove described are included in a piping system, including the pipes 3|, valves i 32 and 32' and branch pipes, as shown; In order toprovide accessto'the'portion of l the strip located between stands .or. traversing the table 25, I preferably so arrange the nozzles constituting the group 26" and a portion of the group 21 that they may be elevated to the dotted line position as shown in Figure 1. This, of

course, refers only to the nozzles located above the table 25 and is accomplished by providing a swivel joint in the piping as shown at 32, 32' in Figure 4.

It will, of course, be apparent that a reel may be associated with the first and last stands of the continuous mill, and that under some conditions 'of operation it may be desirable to surround the coiling reel. with nozzles for delivering cooling lubricant, such as the nozzles 14" of Figure 1. It will also be apparent that various changes in the positioning and the arrangement of the nozzles may be employed and that, while I have'disclosed some. of the nozzles associated" with entering guides, wherein the guides are hollow so as. to provide cooling lubricant delivery passages therein, such an arrangement maybe varied and that the apertures of the guides 'may be replaced by properly located, separately formedjnozzles. The apparatuisillustrated may-be supplemented by any convenient arrangement of-shields. for-preventing loss of such catch basins as are provided. It will also be apparent that thenozzles M of Figure 1 and the nozzles 26. and- 21 .of Figure 2, may be replaced by other expedients for cooling the working rolls, but that the broad intent of the invention is 'to provide an arrangement such that the mechanically produced heat is dissipated substantially as rapidly as it is generated .sothat the material enters the successive passes, whether in a reversing mill or a continuous mill, at sub-.

a stantially the same temperature for each pass.

This is. in general accomplished by subjecting the material being rolled to a heat dissipating mfluence substantially at and immediately tollowing the time of subjecting it to deforming strains, and in so controlling the cooling effect and the duration of the cooling influence as to abstract the greater part of the mechanically generated heat from the strip material before.

the material is subjected. to a subsequent rolling pass. In addition to the above, such heat as may be generated inor may be absorbed by the surfaces of the deforming. rolls is also dissipated,

' or largely offset, by rapidly carrying awaythe 1 heat. atthe surface of the roll, and thusjmaintaining a more or less uniform temperature distribution throughout the body of the roll.

While I prefer to refrigerate the cooling lubricant to temperatures approximating the freezing temperature of water, the delivery temperature of the cooling lubricant, will depend on the rate of lubricant flow, the speed of rolling}. the

amount of reduction per pass and the period intervening between passes: That is to say, un-

der some exceptional conditions of operation, the

desired result may'be accomplished by water cooling the cooler 6, particularly where an adequate flow of low temperature water is available, e. g., from the rivers or lakes during the winter months of theyear. r

In the claims, the word copious as applied to the flow of, a cooling lubricant, is to be understood to mean a sufficiently large quantity to.

substantially cover the sheet with a liquid film-- flowing rapidly with respect to .the surface.

Thus, in efiect, the material. is maintained submerged during the feeding, transferring, rolling, coiling and uncoiling operations. clairns, the words artificially cooled mean cooled Also inthe by a refrigerating machine or other means suitable for producing a temperature considerably below that of the atmosphere.

i From the. foregoing it will be apparent'that various changes, both in the procedure described and in the apparatus contemplated for carrying I out that procedure, may be made without departing from the spirit and scope of my invention as I defined by the appended claims.

What I claim is: 1. A method of cold rolling which includes subjecting the material rolled to successive rolling passes in opposite directions, coiling the material as it issues from each pass and subjecting the material to a copious-high-velocity flow of cooling lubricant substantially asdefined in the specification as it-issues from each pass, as-it moves toward the coiler and during the coiling operation, said lubricant being artificially cooled to a sub-atmospliierictemperature.

2. A method of cold rolling which includes, subjecting strip material to successive rolling passes in opposite directions, coiling the material as it issues from each pass and spraying the material as it issues from each pass as it moves toward the coiler and-as it isbeing coiled with a copious supply of cooling lubricant artificially cooled to's'ubstantially 32 F. and moving at high velocity relative to thematerial.

3. In combination with a rolling mill,'a coiler,

a plurality'of liquid spray nozzles located above and below the path of travel of material issuing from said mill and passing to said'coiler, spray nozzles surrounding said coiler, -a casing partially enveloping said coiler and having a liquid delivery port formed therein, a pump for delivering liquid'under pressure to said spray nozzles and means for delivering liquid'from' said delivery port to'the inlet of said pump.

-4. lncombinationwltharollinlmlllacoller a plurality of spray nozzles spaced between said mill and said coiler and surrounding said coiler, a basin located below said mill and'having a delivery port formed therein, a ,basin located below 5 said coiler and having a delivery port formed therein, a pump for delivering liquid to said nozzles, a cooler intervening between said pump and said nozzles, and piping between said delivery ports and the inlet port to said pump.

- l 5. In combination with a rolling mill, a coiler,

- pray nozzles located between said mill and said coiler and around said coiler, basins for collecting liquid issuing from said nozzles, a pump-for delivering liquid" to said nozzles, a cooler inter-' l vening between said pump and said nozzles,

means for refrigerating the cooling medium delivered to said cooler and means for delivering liquid collected 'in said basins to the inlet of said,v pump.

" 6. In combination with a continuous mill comprising a plurality of stands, a' guide table between adjacent stands having liquid delivery openings formed therein, spray nozzles located in spaced relation between said stands and above and below said table, a basin located below said table, a pump for receiving lubricating liquid from said basins and delivering liquid to said nozzles and a cooler intervening between said pump and said nozzles.

'7. In combination with a continuous mill comprising a plurality of roll stands, hollow delivery guides associated with each such stand and having liquid delivery apertures formed therein,

spray nozzles located in spaced relation between .said stands and above and below the path of travel of material traversing said mill, means for collecting liquid issuing from said apertures and said nozzles, a pumpv communicating with said means for delivering liquid to said, nozzles and 40 said hollow guides, a cooler intervening between i said pump and said nozzles and means for re- 50 apertures, a series ofnozzles located in spaced relation between said stands and movable toward and away from said table, a pump for delivering liquid to said nozzles and to said guides, means for collecting liquid issuing from said nozzles 55 and for delivering liquid -so collected to said pump, a cooler intervening between said pump and said nozzles and means for refrigerating the cooling medium delivered to saidcooler.

9. I'he combination with a reversing mill, a 60 coiler located on each side of said mill, a casing for each coiler having a hinged cover, spray nozzles located in spaced relation'between'said mill and each' of said coilers, spray nozzles associated with said casings and movable with-said cover, a pump, for delivering liquid to' all of.

said spray nozzles, a coolerintervening between said nozzles and said pump, means for receiving liquid delivered from said spray nozzles and delivering such liquid to said pump.

70 10. In' combination with a reversing mill, hollow entrance guides located on each side thereof and having liquid delivery apertures formed therein, a coiler located on each side of said mill, a casing for each coilerhavinga movable 75 cover, spray nozzles located 'in spaced relation above and below the path of travel from said mill to each coiler, spray nozzles associated with each casing and cover and surrounding, said coiler, a pump for delivering liquid under pressure to said spray nozzles and to said hollow 5 4 guides, a cooler intervening between said pump uncoiling the material, and directing the cooled lubricant upon the rolls in such a manner that the material will be reduced to its initial temperatu're before entering each successive-rolling pass.

12. The method of cold rolling suitable material such as strips and sheets which includes, 25 subjecting the material to successive passes between rolls under pressure in a reversing mill, coiling the material as'it comes from a pass, and later uncoiling it as it enters the next pass, cooling the strip to substantially a predetermined 30 fixed temperature by artificial cooling means as it comes from the pass and while coiling and uncoiling it, said temperature being substantially the same for all passes, and subjecting the mate.-

- rial to a succeeding pass immediately after ithas 35 moved through a preceding pass.

13..A method of cold rolling strip metal which includes incrementally roll reducing a work piece from initial to, final gauge and in projecting against the reducing rolls and the top and bot- 40 tom surfaces of the work piece high velocity jets of liquid lubricant having a temperature of about32 F. and in suflicient quantities to cool the rolls and envelop the workpiece with a rapidly moving stream of cooling liquid.

14. A method of cold rolling strip metal which includes passing a work piece through reducing rolls and in projecting liquid lubricant having a temperature of about 32 F. and in the form of 7 jets against said rolls and against the top and bottom surfaces'of the work piece on the entering and exit sides of said rolls and in quantities sufficient to flood the entire work piece wit rapidly moving cooling liquid.

15. A method of cold working strip metal which (includes incrementally roll reducing a workpiece from initial to final gauge and simultaneously with such reductions in projecting jets of liq-' uid lubricant against the reducing rolls and 5 against the ,top and bottom surfaces of the work 4 'tinuously projecting high velocity jets of liquid lubricant maintained at a temperature of about; 32 'F. against'the reducing.rolls and thetop and bottom surfaces of the work piece; the.volv ume of lubricant so projected being suflicient to provide a rapidly moving envelope capable of lowering the temperature of the workpiece l6 to substantially its initial temperature after each such reduction. J

17. A method of cold rolling strip material which includes subjecting a work piece'to successive roll reductions and during and between such reductions inenveloping all portions of uidlubricant formed by projecting against the entire upper and lower surfaces of the same jets of liquid lubricant having a temperature of about 32? F. v

1 9. A method of cold rolling strip material which includes subjecting 'a' work piece'to successive roll reductions and a continuous temperature reducing procedure which consists in contacting its entire upper and lower surfaces with a rapidly moving deluge of liquid lubricant by projecting jets of liquid lubricant cooled-to about 32 F. against such surfaces and against ing mill for 'cold reducing stripmaterial, nozzles the reducing. rolls whereby the temperature of the work piece after each reduction is lowered to'substantially its initial temperature, v

'20. In combination with the rolls of a reverslocated at'both sides of said rnillabove and below the path of travel. of material traversing .the mill and arranged-to project high velocity jets of liquid lubricant along the upper and lower surfaces of such material, a lubricant collector located'below the path of travel of the material, a pump for receiving liquid from said collector and for delivering the same to saidnozzles and a lubricant-cooler located between said vpump and said. nozzles.

21. The combination'with the reducing rolls of a. mill for cold reducing strip metal, of upper and lower-hollow delivery guidesgadjacent said rolls and provided with jet apertures-for pro- 2, jecting liquid lubricant along the. upper and lower surfaces of material entering and leaving the mill, means for collecting liquid flowing from the material being rolled, a pump communicating with saidmeans and arranged to project liquid through Isaidjet apertures, a cool- .er intervening between said pumpand said jet apertures and means for refrigerating the cool?- ing medium delivered to said cooler to ate'mperature such. that the liquid lubricant is projected onto the material, being rolled at a temperature of about 32 F '22. The combination with fthe reducing rolls of a reversing mill for cold reducing strip metal, of liquid delivery nozzles located on opposite sides of said mill and arranged to direct liquid lubricant onto and along the top and bottom surfaces'of the material traversing the mill, a pump for forcibly projecting sufficient liquid lubricant through said nozzles and onto the material being rolled to completely envelop the same, means for collecting liquid delivered by said nozzles and flowing from said material, a cooler intervening between said pump and said nozzles, and means for refrigerating the cooling medium delivered to said cooler whereby the liquid lubricant is delivered by said nozzles at a temperature of about, 32". .F;

23. A method of cold reducing stripmetal which includes subjecting the material to be reduced to successive i'ollreductionsin a reversing mill, coiling ,the'material between re-y ductions and during its travel to and from the mill in projecting onto and along its upper and lower surfaces high velocity jets of liquid lubri cant discharged at 'a temperature of about 32 F. and during coiling in also projecting higlr velocity jets of such lubricant against the outer surface-of the materials 24. A method of cold rolling which includes subjecting strip material to successive reducing passes through which the material alternately moves in opposite directions, coiling the material rial as it issues from 'each pass, as it moves toward the coiler and during coiling high presbetween passes and projecting onto the matesure jets of liquid lubricant cooled to substan tially 32 F. and moving "at a hi h velocity relative to the material. 

